U.S. Pat. No. 4,617,238 to Crivello et al discloses organopolysiloxanes containing at least one Si-bonded vinyloxy-functional group per molecule of the formula EQU H.sub.2 C.dbd.CH--O--G--
where G represents an alkylene radical or an alkylene radical which is interrupted by at least one divalent heteroatom or a combination of heteroatoms. U.S. Pat. No. 4,617,238 describes light-crosslinkable compositions which contain the abovementioned organopolysiloxanes, and also onium salts which catalyze the cationic polymerization of these organopolysiloxanes.
Therefore, it is an object of the present invention to provide organosilicon compounds, in particular silanes and organopolysiloxanes, which contain at least one Si-bonded Y radical of formula (I) per molecule. Another object of the present invention is to provide organosilicon compounds having at least one Si-bonded Y radical of formula (I) which can be prepared from readily available starting materials. Still another object of the present invention is to provide organopolysiloxanes having at least one Si-bonded Y radical of formula (I) per molecule which crosslink rapidly when exposed to light, especially ultraviolet light, during cationic polymerization.